Hitachi Carb

[Mark]

I've connected the hitachi carb and am trying to get it to work,

I've connected the one black wire to a positve so it idles (if disconnected it does not idle). only problem is that it idles at 1500rpm and the choke is on, what do i do with the other 3 wires?

 

[Andrew]

One is a fuel cutoff solenoid, one is the idle control, and one is for the choke heater. Not sure about the other.

 

[Mark]

I've connected the idle control up i believe as when its disconnected the engine stalls.

just cant get it to idle properly, it just sits at 1.5k with the choke on

 

[Arnold]

What about when the engine heats up? does the choke disengage and the RPM drop?

 

[Mark]

nope the engine speed stays the same all the time and the choke is always on.

3 wires out of the 4 are not connected, does anyone know what i connect these three wires to so it will all work properly?

 

[Andrew]

Have you used this carb before? If not, it might be the idle mixture screw that needs adjusting. There is another solenoid on it which ups the revs when the headlights etc. are turned on, this might be stuck.

 

[Andrew]

The choke heater and fuel cut-off solenoid need to go to an ignition supply. The idle control one goes to another wire which should be there.

 

[Mark]

any idea which is which?

my car is an ECC model so might not have the wires there,

 

[Andrew]

I seem to remember that the choke heater ones go into the plastic cap that holds the bimetal coil. The way I worked it out was by trying each wire until it worked.

As for the idle control wire in the car, I think there is one on an ECC car, I have no idea which one it is.

 

[Mark]

i'll give it another go and see what happens, do any of the wires need to be earthed?

dont really want the revs to increase when the lights are on or anything, just want the choke working and for it to idle properly.

 

[Slim]

The problem mark has is quite interesting here, and i also had the same thing last time i woke my E reg K10 up,and presumably the probem is still there.

Mark's car origionally had all the ECC rubish on, which was all quickly ditched as he had a weber car put on. After that he tried an experiment with a custom inlet and an SU carb and now wishes to use a standard Hitatchi DCZ 306 91 carb as found on a facelift MA10 manual. He bought this carb off me, i can can say its always performed and functioned perfectly.

On the standard K10 carbs, there are 4 wires and 2 wiring plugs. The plug on the passenger side can be ignored - this is purely for the idle-up system which is a solenoid that richens the mixture when an electrical load causes the idle speed to drop. This is too much hastle to wire in as its currently combined with the ECC ECU system which is totally disconected. To all intents and purposes, this will not affect the every day running of the car.

The 2nd wiring plug is the one that is required. 1 of the wires needs to be conected to +ve when the ignition switch is in position ON and START, in order to supply the anti dieseling valve with power. As far as i understand, he has this wired up correctly and there isnt a problem with it.

The problem lies with the other wire, which goes from the wiring block to the auto choke housing on the back of the carb. I do not understand how it all works but i know that when he has put 12v to this wire, which is presumably the bi metalic heater strip or something, it has made no difference.

And when he mentions that its idling at 1500 and the choke is stuck on, he means the choke flap is phyically half closed as it would be on a cold start utilising the choke, and it wont come off. If this problem is the same as the one that i have, if you use a screwdriver or a person with small fingers to close the choke flap (i.e. take the restriction away from the venturi) then the engine will die and also it is quite apparant that the choke is being held open by a spring.

Any clues as to what voltage the wire to the choke unit should have at various stages i.e. initial start, after a few minutes and when off choke etc should be very usefull, as well as information on what actually controls the choke unit.

I hope this has cleared a few things up, and explained the problem in detail.

 

[ohc_turbo]

id say give it some carb cleaner, check the linkage isnt stretched

 

[Andrew]

The choke heater is just 12V - it may be two wires though. It just turns on, the bimetal strip takes a certain amount of time to open the choke flap up fully, and it depends slightly on ambient temperature.

 

[Slim]

so if 12v is being given to the choke heater, why isn't it working. And musn't there be an earth involved somewhere as well?

Presumably, the idle-up solenoid works in exactly the same way as the anti dieseling solenoid, but the anti dieseling solenoid has 1 wire from it and the idle-up solenoid has 2, so therefor is it possible that 1 of the wires to the idle-up solenoid acts as an earth to the carb, which in turn affects the circuit for the auto choke heater?